Unit5语法专项课件 ——形式主语it & 形容词+enough+to+动词课件 2025-2026学年沪教版八年级英语下册

教学课件 沪教（牛津）英语八年级下册 Unit5语法专项—— 形式主语it & 形容词+enough+to+动词 全解精讲+分层练习 1 学习目标 1. 熟练掌握形式主语it的两种核心结构及用法 2. 吃透“形容词+enough+to+动词”结构，掌握否定转换 3. 能准确区分形式主语it中for与of的用法差异 4. 熟练完成填空、选择、改写、翻译等多种题型 5. 能在动物保护相关语境中灵活运用本单元语法 形式主语it的核心概念 当句子的真正主语是较长的不定式短语时，我们用it作形式主语， 将真正的主语（不定式短语）放在句子末尾，使句子结构更平衡。 注意：it在此处无实际含义，仅起占位作用，不能省略。 核心目的：避免主语过长，让句子更简洁、易读。 形式主语it（结构一：for sb.） 核心结构：It + be + 形容词 + for sb. + to do sth. 用法说明：此处的形容词修饰“做某事”这个动作， 说明“做某事对某人来说是……的”，sb.是动作的执行者。 例句：It is important for us to protect endangered animals. （保护濒危动物对我们来说很重要。） 形式主语it（for sb. 拓展例句） 1. It is necessary for everyone to follow the rules. （遵守规则对每个人来说都是必要的。） 2. It is useful for students to learn English well. （学好英语对学生来说很有用。） 3. It is difficult for the old man to carry the box. （对这位老人来说，搬这个箱子很难。） 形式主语it（结构二：of sb.） 核心结构：It + be + 形容词 + of sb. + to do sth. 用法说明：此处的形容词描述“某人”的品质、性格， 说明“某人做某事是……的”，sb.是动作的发出者，且有良好/不良品质。 例句：It was kind of her to help the injured bird. （她帮助那只受伤的鸟，真是太善良了。） 形式主语it（of sb. 拓展例句） 1. It is selfish of some people to destroy animal habitats. （有些人破坏动物栖息地，真是太自私了。） 2. It was brave of him to stop the illegal hunting. （他阻止非法捕猎，真是太勇敢了。） 3. It is silly of you to make such a mistake. （你犯这样的错误，真是太傻了。） for与of的核心区别（表格） 用法 形容词特点 例句 for sb. 修饰动作，无品质倾向 It is important for us to study. of sb. 描述人的品质、性格 It is kind of you to help me. 小技巧：形容词后可加sb.（如kind of you）用of，否则用for。 形式主语it 易错题提醒 1. 不可省略it，误写为“Is important to study.”（缺it） 2. 混淆for与of，误写为“It is kind for you to help.” 3. 不定式短语不可漏to，误写为“It is necessary for us study.” 4. be动词要与形容词搭配，保持主谓一致。 “形容词+enough+to+动词”核心概念 该结构表示“某人/某物具备足够的某种特质，能够完成某个动作”。 核心逻辑：足够的程度 → 能够达成的动作，语气肯定。 注意：enough修饰形容词时，必须放在形容词的后面，不可前置。 例句：The boy is strong enough to lift the stone. （男孩足够强壮，能举石头。） “形容词+enough+to+动词” 肯定句拓展 1. The volunteer is patient enough to take care of the baby panda. （这位志愿者足够有耐心，能照顾熊猫宝宝。） 2. We are energetic enough to collect money for wildlife. （我们足够有活力，能为野生动物筹款。） 3. The river is clean enough for animals to drink. （这条河足够干净，动物可以饮用。） “形容词+enough+to+动词” 否定转换 否定含义可表达为：主语 + be + not + 形容词 + enough + to + 动词原形 也可转换为：主语 + be + too + 形容词的反义词 + to + 动词原形 例句：The bird is not strong enough to fly. = The bird is too weak to fly. （这只鸟不够强壮，飞不起来。） 否定转换 拓展例句 1. The baby elephant is not big enough to find food alone. = The baby elephant is too small to find food alone. （小象不够大，不能独自觅食。） 2. She is not tall enough to reach the book. = She is too short to reach the book. （她不够高，够不到那本书。） “形容词+enough+to+动词” 易错题提醒 1. enough位置错误，误写为“enough strong to lift”（需后置） 2. 否定转换时，反义词使用错误（如strong的反义词是weak） 3. 不定式漏to，误写为“is strong enough lift the box” 4. 混淆“too...to...”与“enough...to...”的语气（too...to...表否定） 习题一：用for或of填空 请根据句意，在横线上填入for或of，注意区分用法。 1. It is necessary ___________ us to protect animal homes. 2. It was brave ___________ her to stop the hunter. 3. It is helpful ___________ students to join environmental groups. 4. It is selfish ___________ him to destroy the forest. 5. It is useful ___________ everyone to learn animal protection knowledge. for of for of for 习题一：用for或of填空 6. It was kind ___________ your teacher to help you with the task. 7. It is wrong ___________ people to hunt endangered animals. 8. It is difficult ___________ the zookeeper to take care of many animals. 9. It is clever ___________ the boy to find the lost bird. 10. It is important ___________ us to keep the environment clean. of of for of for 习题二：用“形容词+enough+to+动词”完成句子 1. The baby panda is _____________________ (not / big / eat) bamboo alone. 2. We are ______________________ (old / help) protect the wild animals. 3. The bird was ___________________________ (weak / fly) after being hurt. 4. The volunteer is _________________ (patient / look after) the injured duck. 5. The river is ________________________ (not / clean / drink) for the fish. not big enough to eat old enough to help too weak to fly patient enough to look after not clean enough to drink 习题二：用“形容词+enough+to+动词”完成句子 6. We are ____________________ (smart / find) ways to save the pandas. 7. The little girl was ___________________ (not / tall / reach) the bird’s nest. 8. The zookeeper is ___________ (experienced / deal with) animal emergencies. 9. The boy is _____________________________ (strong / carry) the heavy box. 10. The old man is _____________________ (not / energetic / walk) a long way. smart enough to find not tall enough to reach experienced enough to deal with strong enough to carry not energetic enough to walk 习题三：单项选择（语法辨析） 1. ___________ important ___________ us to learn about wildlife. A. It; for B. It; of C. That; for 2. The elephant is ___________ to carry the heavy log. A. strong enough B. enough strong C. too strong 3. It was ___________ of her to help the homeless animal. A. kind B. for C. of A A A 习题三：单项选择 4. The baby sheep is ___________ to feed itself. A. not big enough B. enough big C. too big 5. ___________ cruel ___________ people to kill the tigers. A. It; for B. It; of C. That; of 6. She is ___________ to finish the task by herself. A. enough clever B. clever enough C. too clever 7. It is necessary ___________ everyone to follow the rules. A. for B. of C. to A B B A 习题四：用形式主语it改写句子 将下列句子用形式主语it改写，保持句意不变，注意for/of用法。 1. To protect the environment is necessary. → ________________________________________ 2. To join the wildlife protection group is helpful for us. → ________________________________________ 3. To help the injured animal is kind of you. → ________________________________________ It is necessary to protect the environment.  It is helpful for us to join the wildlife protection group.  It is kind of you to help the injured animal. 习题四：用形式主语it改写句子 4. To learn about endangered animals is useful. → ________________________________________ 5. To destroy animal habitats is wrong of some people. → ________________________________________ 6. To carry the heavy box is difficult for the old man. → ________________________________________ 7. To help raise money for wildlife is kind of them. → ________________________________________ It is useful to learn about endangered animals. It is wrong of some people to destroy animal habitats. It is difficult for the old man to carry the heavy box.  It is kind of them to help raise money for wildlife. 习题五：句子改写（否定转换） 将下列句子改为否定形式，并用too...to...转换（每句两种表达）。 1. The boy is strong enough to lift the stone. → ________________________________________ → ________________________________________ 2. The girl is tall enough to reach the book. → ________________________________________ → ________________________________________ The boy is not strong enough to lift the stone. The boy is too weak to lift the stone. The girl is not tall enough to reach the book. The girl is too short to reach the book. 习题六：翻译句子（综合运用） （形式主语it或enough结构） 1. 对我们来说，保护濒危动物很重要。 → ________________________________________ 2. 他帮助受伤的野生动物，真是太善良了。 → ________________________________________ 3. 这头小象还不够大，不能自己找食物。 → ________________________________________  It is very important for us to protect endangered animals. It is very kind of him to help injured wild animals. The baby elephant is not big enough to find food by itself. 习题六：翻译句子（拓展提升） 4. 我们足够勇敢，可以阻止非法捕猎。 → ________________________________________ 5. 人们破坏动物家园是自私的。 → ________________________________________ 6. 这条河不够干净，不能让动物饮用。 → ________________________________________ 7. 对学生来说，了解动物保护知识很有用。 → ________________________________________ We are brave enough to stop illegal hunting.  It is selfish of people to destroy animals' homes. The river is not clean enough for animals to drink.  It is very useful for students to learn about animal protection knowledge. 核心语法总结（一） 一、形式主语it的两种结构 1. It + be + 形容词 + for sb. + to do sth.（修饰动作） 2. It + be + 形容词 + of sb. + to do sth.（描述人的品质） 关键：for表“对某人来说”，of表“某人的品质” 注意：it不可省略，不定式短语不可漏to。 核心语法总结（二） 二、“形容词+enough+to+动词”结构 1. 肯定：主语 + be + 形容词 + enough + to + 动词原形 2. 否定：not + 形容词 + enough + to do = too + 反义词 + to do 关键：enough必须放在形容词后面，不可前置。 适用场景：描述能力、程度，贴合动物保护语境。 易错点汇总（重点记忆） 1. for与of混淆：形容词描述人用of，修饰动作用for。 2. enough位置错误：修饰形容词，后置不前置。 3. 形式主语it遗漏：不可直接省略it开头。 4. 不定式漏to：两种语法结构中，to不可省略。 5. 否定转换反义词错误：如strong→weak，big→small。 教学课件 Unit5语法专项—— 形式主语it & 形容词+enough+to+动词 Thank you for listening! 29 $